CN111405708B - Bleeder control system, silicon controlled rectifier dimming phase angle detection circuit and method - Google Patents
Bleeder control system, silicon controlled rectifier dimming phase angle detection circuit and method Download PDFInfo
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- CN111405708B CN111405708B CN201811535760.7A CN201811535760A CN111405708B CN 111405708 B CN111405708 B CN 111405708B CN 201811535760 A CN201811535760 A CN 201811535760A CN 111405708 B CN111405708 B CN 111405708B
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Abstract
The invention provides a discharge control system, a silicon controlled rectifier dimming phase angle detection circuit and a method, wherein the discharge control system comprises: a bus voltage detection module; a first comparison module for generating a pulse width modulation signal; the on-time signal generating module generates an on-time signal of the silicon controlled dimmer; a digital filtering module for filtering the on-time signal; and the second comparison module is used for comparing the output voltage of the digital filtering module with the leakage threshold voltage so as to generate a leakage control signal. Generating a bleed current when the DC voltage of the on-time signal is less than a bleed threshold voltage; and when the direct current voltage of the on-time signal is greater than the bleeder threshold voltage, the bleeder current is turned off. The phase angle detection circuit is integrated in the chip by using the digital filter, so that an external capacitor is not needed, the number of chip pins is saved, and the system cost is reduced; meanwhile, the bleeder circuit is integrated in the chip, so that peripheral application circuits are simplified; in addition, the invention can set the dimming curves with different phase angles by the dimming control signal.
Description
Technical Field
The invention relates to the field of integrated circuit design, in particular to a discharge control system, a silicon controlled rectifier dimming phase angle detection circuit and a silicon controlled rectifier dimming phase angle detection method.
Background
The thyristor is a high-power semiconductor device with a four-layer structure of three PN junctions, and is generally formed by reversely connecting two thyristors. Its function is not only rectification, but also quick switching on or off of a contactless switch; the inversion of converting direct current into alternating current is realized; changing an alternating current of one frequency to an alternating current of another frequency, and so on. The controllable silicon has the advantages of small volume, high efficiency, good stability, reliable work and the like, as with other semiconductor devices. The emergence of the semiconductor device enables the semiconductor technology to enter the strong current field from the weak current field, and becomes an element which is adopted in the fields of industry, agriculture, transportation, military scientific research, commercial and civil electric appliances and the like. At present, the controllable silicon is widely applied to the aspects of automatic control, electromechanical application, industrial electricity, household appliances and the like.
However, in the triac dimming scheme, there is a problem of compatibility between the LED and the triac. The current flowing through the silicon controlled rectifier is required to be more than or equal to the holding current of the silicon controlled rectifier, so that the silicon controlled rectifier can work stably and reliably, otherwise, the silicon controlled rectifier can work intermittently or not work, and the phenomenon of LED flicker occurs. Therefore, a bleeder circuit is usually required to generate a bleeder current when the LED is not turned on, so that the current flowing through the thyristor is larger than the holding current thereof, thereby ensuring reliable conduction of the thyristor.
Since the leakage current is a substantial loss for the whole system, the system efficiency is reduced, so that the leakage circuit is not needed to work when the thyristor dimmer is not connected, and whether the leakage current needs to be added or not can be judged by detecting the input voltage.
Therefore, how to reduce the system cost and simplify the peripheral circuit while ensuring the stable operation of the thyristor has become one of the problems to be solved by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a bleeding control system, a thyristor dimming phase angle detection circuit and a method thereof, which are used to solve the problems of high cost, complex peripheral circuit and the like in the prior art for controlling the bleeding current.
To achieve the above and other related objects, the present invention provides a silicon controlled rectifier dimming phase angle detection circuit, which at least comprises:
the bus voltage detection module receives and detects bus voltage;
the first comparison module is connected to the output end of the bus voltage detection module and compares the detection voltage of the bus voltage with the preset bus detection voltage to generate a pulse width modulation signal;
the on-time signal generating module is connected to the output end of the first comparing module and generates an on-time signal of the silicon controlled rectifier dimmer based on the pulse width modulation signal;
the digital filtering module is connected to the output end of the on-time signal generating module and is used for filtering the on-time signal;
the second comparison module is connected to the output end of the digital filtering module and compares the output voltage of the digital filtering module with the bleeding threshold voltage so as to generate a bleeding control signal; when the output voltage of the digital filtering module is smaller than the bleeding threshold voltage, the bleeding control signal controls to generate a bleeding current; when the output voltage of the digital filtering module is greater than the bleeding threshold voltage, the bleeding control signal controls the bleeding current to be turned off.
Preferably, the on-time signal generating module includes a first switch and a first resistor, one end of the first switch receives a reference voltage, and the other end of the first switch is grounded through the first resistor, the first switch is controlled by the pwm signal, and the on-time signal is output at a connection node between the first switch and the first resistor.
Preferably, the digital filtering module includes an adder, a second switch, a third switch, a first capacitor and a second capacitor;
the input end of the second switch is connected with the output end of the digital filtering module, and the output end of the second switch is connected with the upper polar plate of the first capacitor, so that the output voltage of the digital filtering module is sampled; the lower polar plate of the first capacitor is grounded;
a first input end of the adder is connected with an output end of the second switch, and a second input end of the adder receives the on-time signal and is used for performing addition operation;
the input end of the third switch is connected with the output end of the adder, and the output end of the third switch is used as the output end of the digital filtering module and is used for sampling the output signal of the adder;
the upper polar plate of the second capacitor is connected with the output end of the third switch, and the lower polar plate is grounded;
wherein the control signals of the second switch and the third switch have opposite polarities.
More preferably, the capacitance of the first capacitor and the capacitance of the second capacitor are in the pF class.
More preferably, the digital filtering module further comprises a follower connected between the output terminal of the third switch and the output terminal of the digital filtering module, for isolating the signal.
More preferably, the digital filtering module further includes a switch control signal generating unit; the switch control signal generating unit comprises a high-frequency sampler and an inverter, wherein the high-frequency sampler is used for generating square wave signals; the phase inverter is connected with the output end of the high-frequency sampler and is used for generating an inverse signal of the output signal of the high-frequency sampler.
Preferably, the silicon controlled rectifier dimming phase angle detection circuit further comprises a reference voltage generation module, wherein the reference voltage generation module is connected to the output end of the digital filtering module, receives the dimming control signal, and generates a corresponding reference voltage according to the output voltage of the digital filtering module and the dimming control signal.
More preferably, the reference voltage generating module includes a dimming unit and a clamping unit;
the dimming unit receives the output voltage of the digital filtering module and the dimming control signal and adjusts the waveform of the reference voltage based on the dimming control signal;
the clamping unit is connected to the output end of the dimming unit, and when the conduction time signal of the silicon controlled dimmer is larger than the maximum conduction time of the LED, the reference voltage clamp is positioned at a set reference voltage.
More preferably, the clamping unit comprises a second resistor, a comparator and a pull-down tube; one end of the second resistor is connected with the output end of the dimming unit, and the other end of the second resistor is used as the output end of the clamping unit; the input end of the comparator is respectively connected with the output end of the clamping unit and the set reference voltage; one end of the pull-down tube is connected with the output end of the dimming unit, the other end of the pull-down tube is grounded, and the control end of the pull-down tube is connected with the output end of the comparator.
In order to achieve the above and other related objects, the present invention provides a method for detecting a dimming phase angle of a thyristor, the method at least comprising:
detecting bus voltage to obtain a conduction time signal of the silicon controlled dimmer, and digitally filtering the conduction time signal to obtain corresponding direct current voltage;
comparing the direct current voltage of the conduction time signal with a leakage threshold voltage to generate a leakage control signal, and generating a leakage current when the direct current voltage of the conduction time signal is smaller than the leakage threshold voltage; and when the direct current voltage of the on-time signal is greater than the bleeding threshold voltage, the bleeding current is turned off.
Preferably, the method for detecting the silicon controlled rectifier dimming phase angle further comprises generating a corresponding reference voltage based on the direct current voltage of the on-time signal and the dimming control signal;
when the on-time signal is less than the minimum on-time, the reference voltage is zero; when the on-time signal is greater than the maximum on-time, the reference voltage clamp is at a set reference voltage; when the on-time signal is between the minimum on-time and the maximum on-time, adjusting the waveform of the reference voltage based on the dimming control signal;
the minimum conduction time is the time detected by a phase cut angle of the silicon controlled dimmer after the bus voltage drop LED cannot be conducted; the maximum on-time is the maximum on-time of the LED.
More preferably, the minimum on-time and the maximum on-time satisfy the following relation:
wherein, Ton_maxIs the maximum on-time, VLEDIs the on-voltage of the LED, Vin_maxIs the peak value of the bus voltage, T is the period of the bus voltage, Ton_minTo said minimum on-time, Vb′usIs a preset bus voltage.
To achieve the above and other related objects, the present invention provides a bleed-off control system, comprising at least:
the silicon controlled rectifier dimming phase angle detection circuit and the bleeder circuit;
the silicon controlled dimming phase angle detection circuit detects bus voltage to obtain a conduction time signal of the silicon controlled dimmer, and compares direct current voltage subjected to digital filtering of the conduction time signal with a discharge threshold voltage to obtain a discharge control signal;
the discharging circuit is connected with the output end of the silicon controlled dimming phase angle detection circuit, current discharging is controlled according to the discharging control signal, and discharging current is larger than maintaining current of the silicon controlled dimmer.
Preferably, the bleeder circuit comprises a bleeder tube, a third comparison module, a feedback resistor and a bleeder current regulating resistor; the discharge tube is connected with the discharge current regulating resistor in series and then connected with two ends of the bus voltage in parallel; the first end of the feedback resistor is connected between the discharge pipe and the discharge current regulating resistor; the first input end of the third comparison module is connected with the output end of the silicon controlled rectifier dimming phase angle detection circuit and the second end of the feedback resistor, the first input end of the third comparison module is connected with the discharge reference voltage, and the output end of the third comparison module is connected with the control end of the discharge pipe.
Preferably, the bleed-off control system further comprises a first diode and a second diode; the positive electrode of the first diode is connected with the output of the silicon controlled rectifier dimming phase angle detection circuit, and the negative electrode of the first diode is connected with the input end of the bleeder circuit; and the anode of the second diode is connected with a discharge turn-off signal, and the cathode of the second diode is connected with the input end of the discharge circuit.
As described above, the bleeding control system, the silicon controlled rectifier dimming phase angle detection circuit and the method of the present invention have the following advantages:
1. the invention can integrate the phase angle detection circuit in the chip by using the digital filter, and the external part does not need to use a capacitor, thereby saving the number of chip pins and reducing the system cost.
2. The invention can integrate the bleeder circuit in the chip, and simplify the peripheral application circuit.
3. The invention can set the dimming curves with different phase angles by the dimming control signal.
Drawings
FIG. 1 is a schematic diagram illustrating the principle of the present invention for determining whether a bleed current needs to be added.
Fig. 2 is a schematic structural diagram of the thyristor dimming phase angle detection circuit according to the present invention.
Fig. 3 is a schematic diagram showing a real-time variation curve of the bus voltage according to the present invention.
FIG. 4 is a graph illustrating a relationship between a reference voltage and a turn-on time according to the present invention.
Fig. 5 is a schematic structural diagram of the bleed control system of the present invention.
Description of the element reference numerals
1 silicon controlled rectifier phase angle detection circuit that adjusts luminance
11 bus voltage detection module
12 first comparison module
13 on-time signal generating module
14 digital filtering module
141 adder
142 follower
143 switch control signal generating unit
1431 high frequency sampler
1432 inverter
15 second comparison module
16 reference voltage generation module
161 dimming unit
162 clamping unit
1621 comparator
2 bleeder circuit
21 third comparing module
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 1 to 5. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
As shown in fig. 1, the input voltage (or bus voltage) Vin is an absolute value of the ac input voltage, and when the triac dimmer is connected to the circuit, the detected voltage Vin' of the bus voltage shows that the input voltage Vin is cut off, and the on-time ton is shorter than the cycle time T.
Example one
As shown in fig. 2, the present embodiment provides a thyristor dimming phase angle detection circuit 1, where the thyristor dimming phase angle detection circuit 1 includes:
the bus voltage detection module 11, the first comparison module 12, the on-time signal generation module 13, the digital filtering module 14, the second comparison module 15 and the reference voltage generation module 16.
As shown in fig. 2, the bus voltage detection module 11 receives and detects a bus voltage Vin.
Specifically, in this embodiment, the bus voltage detecting module 11 includes a third resistor R3 and a fourth resistor R4, the third resistor R3 and the fourth resistor R4 are connected in series and then connected in parallel between the bus voltage Vin and ground, and a connection node between the third resistor R3 and the fourth resistor R4 outputs a bus voltage detection voltage.
As shown in fig. 2, the first comparing module 12 is connected to the output end of the bus voltage detecting module 11, and compares the detected voltage of the bus voltage with a preset bus detected voltage Vbus to generate a pulse width modulation signal PWM.
Specifically, in this embodiment, a positive phase input end of the first comparing module 12 is connected to an output end of the bus voltage detecting module 11, and a negative phase input end of the first comparing module receives the preset bus detection voltage Vbus, and an output end of the first comparing module outputs the pulse width modulation signal PWM, where the pulse width modulation signal PWM is related to the thyristor phase cut angle, and can be used by a subsequent circuit to confirm the thyristor phase cut angle or other purposes, which is not described herein. When the detection voltage of the bus voltage is greater than the preset bus detection voltage Vbus, the first comparing module 12 outputs a high level; when the detection voltage of the bus voltage is less than the preset bus detection voltage Vbus, the first comparing module 12 outputs a low level. In this embodiment, the first comparing module 12 is implemented by using an operational amplifier.
As shown in fig. 2, the on-time signal generating module 13 is connected to the output end of the first comparing module 12, and generates an on-time signal Ton of the triac dimmer based on the pulse width modulation signal PWM.
Specifically, in the present embodiment, the on-time signal generating module 13 includes a first switch S1 and a first resistor R1, one end of the first switch S1 receives the reference signal Ref, the other end is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded; the first switch S1 is controlled by the PWM signal PWM, and outputs the on-time signal Ton at a connection node between the first switch S1 and the first resistor R1, where the on-time signal Ton is a square wave signal.
As shown in fig. 2, the digital filtering module 14 is connected to the output end of the on-time signal generating module 13, and performs filtering processing on the on-time signal Ton to obtain a dc voltage.
Specifically, the digital filter module 14 includes an adder 141, a second switch S2, a third switch S3, a first capacitor C1, a second capacitor C2, a follower 142, and a switch control signal generating unit 143.
More specifically, the input terminal of the second switch S2 is connected to the output terminal of the digital filter module 14, and the output terminal of the second switch S2 is connected to the upper plate of the first capacitor C1, so as to sample the output signal Vb of the digital filter module 14; the lower plate of the first capacitor C1 is grounded, and the capacitance value of the first capacitor C1 is in pF level.
The adder 141 has a first input terminal connected to the output terminal of the second switch S2, and a second input terminal receiving the on-time signal Ton for addition.
The input terminal of the third switch S3 is connected to the output terminal of the adder 141, and the output terminal of the third switch S3 is connected to the input terminal of the follower 142, so as to sample the output signal of the adder 141.
The upper plate of the second capacitor C2 is connected with the output end of the third switch S3, the lower plate is grounded, and the capacitance value of the second capacitor C2 is pF level. Wherein the second switch S2 has a control signal polarity opposite to that of the third switch S3.
The output end of the follower 142 is connected to the output end of the digital filtering module 14, in this embodiment, the follower 142 is implemented by using an operational amplifier, a positive input end of the operational amplifier is used as the input end of the follower 142, and a negative input end of the operational amplifier is connected to the output end of the operational amplifier and is used as the output end of the follower 142 for isolating signals.
The switch control signal generating unit 143 includes a high frequency sampler 1431 and an inverter 1432, the high frequency sampler 1431 is configured to generate a square wave signal, and the inverter 1432 is connected to an output terminal of the high frequency sampler 1431 and configured to generate an inverse signal of an output signal of the high frequency sampler 1431; in this embodiment, the output signal of the high frequency sampler 1431 controls the second switch S2, and the output signal of the inverter 1432 controls the third switch S3, which is not limited to the connection relationship of this embodiment in practical use.
As shown in fig. 2, the second comparing module 15 is connected to an output terminal of the digital filtering module 14, and compares the output voltage Vb of the digital filtering module 14 with a bleeding threshold voltage Bleed Set, so as to generate a bleeding control signal Bleed control.
Specifically, in this embodiment, a non-inverting input terminal of the second comparing module 15 is connected to an output terminal of the digital filtering module 14, and an inverting input terminal thereof receives the bleeding threshold voltage Bleed Set. In this embodiment, when the output voltage Vb of the digital filtering module 14 is less than the Bleed-off threshold voltage Bleed Set, the Bleed-off control signal Bleed control is at a low level, and the Bleed-off current is controlled to be generated; when the output voltage Vb of the digital filtering module 14 is greater than the Bleed-off threshold voltage Bleed Set, the Bleed-off control signal Bleed control is at a high level, and the Bleed-off current is controlled to be turned off.
As shown in fig. 2, the reference voltage generating module 16 is connected to the output terminal of the digital filtering module 14, receives the dimming control signal Dim, and generates a corresponding reference voltage CS Ref according to the output voltage Vb of the digital filtering module 14 and the dimming control signal Dim.
Specifically, as shown in fig. 2, the reference voltage generating module 16 includes a dimming unit 161 and a clamping unit 162.
More specifically, the dimming unit 161 receives the output voltage Vb of the digital filter module 14 and the dimming control signal Dim curve, and adjusts the waveform of the reference voltage CS Ref based on the dimming control signal Dim curve. The structure of the dimming unit 161 is not limited, and any circuit capable of realizing the dimming function is suitable for the present invention, which is not described herein again.
More specifically, the clamping unit 162 is connected to the output end of the dimming unit 161, and clamps the reference voltage CS Ref to a set reference voltage LED Ref when the on-time signal Ton of the triac dimmer is greater than the maximum LED on-time. In the present embodiment, the clamping unit 162 includes a second resistor R2, a comparator 1621, and a pull-down tube Q1. One end of the second resistor R2 is connected to the output end of the dimming unit 161, the other end is connected to the non-inverting input end of the comparator 1621, and the inverting input end of the comparator 1621 receives the setting reference voltage LED Ref; the drain terminal of the pull-down tube Q1 is connected to the output terminal of the dimming unit 161, and the source terminal is grounded, and the gate terminal of the pull-down tube Q1 is connected to the output terminal of the comparator 1621. In this embodiment, the pull-down transistor Q1 is an NMOS, and in practical use, the pull-down transistor Q1 may be replaced by another device capable of implementing a pull-down function, which is not limited to this embodiment.
It should be noted that the input/output connection relationships of the comparison modules and the comparators can be set as required, and the same logic relationship can be obtained by adding inverters to different connection relationships, which is not limited to this embodiment.
In this embodiment, since the first capacitor C1 and the second capacitor C2 are pF stages, the silicon controlled rectifier dimming phase angle detection circuit 1 can be integrated into a chip, thereby greatly simplifying peripheral circuits and reducing chip pins and cost.
The operating principle of the silicon controlled rectifier dimming phase angle detection circuit 1 is as follows:
1) and detecting the bus voltage to obtain a conduction time signal of the silicon controlled dimmer, and digitally filtering the conduction time signal to obtain corresponding direct current voltage.
Specifically, voltage division detection is performed on the bus voltage Vin based on the bus voltage detection module 11 to obtain a detection voltage of the bus voltage, the detection voltage of the bus voltage is compared with the preset bus detection voltage Vbus to generate a pulse width modulation signal PWM, and the pulse width modulation signal PWM can be used for confirming a silicon controlled rectifier phase cutting angle.
And generating a conduction time signal Ton of the silicon controlled rectifier dimmer based on the pulse width modulation signal PWM control switch signal, wherein the conduction time signal Ton of the silicon controlled rectifier dimmer is a square wave signal, and performing digital filtering on the conduction time signal Ton to obtain direct current voltage Vb.
2) Comparing the direct-current voltage Vb of the on-time signal Ton with a bleeding threshold voltage Bleed Set to generate a bleeding control signal Bleed control, and generating a bleeding current when the direct-current voltage Vb of the on-time signal Ton is smaller than the bleeding threshold voltage Bleed Set, wherein the bleeding current is larger than a holding current of the thyristor dimmer; when the direct current voltage Vb of the on-time signal Ton is greater than the bleeding threshold voltage Bleed Set, the bleeding current is turned off, and the current flowing through the LED is generally greater than the holding current of the triac dimmer.
3) A corresponding reference voltage CS Ref is generated based on the dc voltage Vb of the on-time signal Ton and the dimming control signal Dim curve.
Specifically, as shown in fig. 3, as the bus voltage Vin increases, a time that the bus voltage Vin is greater than the conduction voltage VLED of the LED is the maximum LED conduction time Ton _ max, and the following relationship is satisfied:
with the reduction of the bus voltage Vin, when the bus voltage Vin is smaller than the conduction voltage of the LED and larger than a preset bus voltage V'busAnd then, the minimum conduction time Ton _ min is detected by the silicon controlled phase-cut angle after the LED cannot be conducted, and the following relation is satisfied:
wherein Ton _ max is the maximum conduction time, VLED is the conduction voltage of the LED, Vin _ max is the peak value of the bus voltage, T is the period of the bus voltage, and Ton _ min is the minimum conduction timeTime, V'busIs a preset bus voltage.
As shown in fig. 4, when the on-time signal Ton is smaller than the minimum on-time Ton _ min, the LED cannot be turned on, and the reference voltage CS Ref is zero. Adjusting the waveform of the reference voltage CS ref based on the dimming control signal Dim current when the on-time signal Ton is between the minimum on-time Ton _ min and the maximum on-time Ton _ max; in this embodiment, the reference voltage CS ref varies linearly, and a curve variation manner can be set according to actual needs, which is not limited in this embodiment. When the on-time signal Ton is greater than the maximum on-time Ton _ max, the on-time of the LED is unchanged, and the reference voltage CS ref is clamped to the set reference voltage LED ref. The reference voltage CS ref serves as a reference for subsequent peripheral circuits.
It is noted that step 2) and step 3) are performed simultaneously; in addition, the present embodiment is exemplified by LED driving, and is not limited to the field of LED driving in practical use, and is not limited to the present embodiment.
Example two
As shown in fig. 5, the present embodiment provides a bleed-off control system, including:
the silicon controlled rectifier dimming phase angle detection circuit 1 and the bleeder circuit 2.
As shown in fig. 5, the silicon controlled dimming phase angle detection circuit 1 detects a bus voltage Vin to obtain an on-time signal Ton of the silicon controlled dimmer, and compares a dc voltage Vb obtained by digitally filtering the on-time signal Ton with a Bleed threshold voltage Bleed Set to obtain a Bleed Control signal Bleed Control.
The specific circuit structure and principle are consistent with the embodiments, and are not repeated herein.
As shown in fig. 5, the bleeding circuit 2 is connected to the output end of the scr dimming phase angle detection circuit 1, and controls current bleeding according to the bleeding Control signal Bleed Control, where the bleeding current is greater than the holding current of the scr dimmer.
Specifically, the bleeder circuit 2 includes a bleeder tube Q2, a third comparing module 21, a feedback resistor Rfb, and a bleeder current adjusting resistor Rdn. The bleeder tube Q2 is connected in series with the bleeder current adjusting resistor Rdn and then connected in parallel with two ends of the bus voltage Vin. The first end of the feedback resistor Rfb is connected between the discharging tube Q2 and the discharging current adjusting resistor Rdn, and the second end is connected to the inverting input end of the third comparing module 21. The inverting input terminal of the third comparing module 21 is further connected to the output terminal of the silicon controlled dimming phase angle detecting circuit 1 through a first diode D1, and is connected to the discharging off signal Bleed off through a second diode D2, the non-inverting input terminal of the third comparing module 21 is connected to the discharging reference voltage Bleed ref, and the output terminal of the third comparing module 21 is connected to the gate terminal of the discharging pipe Q2.
It should be noted that, in this embodiment, the bleeder Q2 is an NMOS transistor, and may be replaced by any device capable of turning on and off a bleeder current in practical use, which is not limited to this embodiment. The input/output connection relationship of the third comparing module 21 can be set as required, and different connection relationships can obtain the same logic relationship by adding an inverter, which is not limited in this embodiment.
It should be noted that the Bleed off signal Bleed off is an additional increased signal, and the first diode D1 and the second diode D2 may be omitted in the case where the Bleed off signal Bleed off is not set.
The principle of the bleeding control system is similar to that of the embodiment, and is not repeated herein.
In the bleeder control system of the embodiment, the bleeder circuit is arranged in the chip, so that a peripheral application circuit can be simplified; further set up bleeder current regulation resistance Rdn in the chip outside, adjustable bleeder current's size increases the application scope of flexibility and chip.
In summary, the present invention provides a bleeding control system, a thyristor dimming phase angle detection circuit and a method thereof, including: a bus voltage detection module; a first comparison module for generating a pulse width modulation signal; a conduction time signal generating module for generating a conduction time signal of the silicon controlled dimmer based on the pulse width modulation signal; the digital filtering module is used for filtering the on-time signal; and the second comparison module is used for comparing the output voltage of the digital filtering module with the leakage threshold voltage so as to generate a leakage control signal. When the direct current voltage of the conduction time signal is smaller than the leakage threshold voltage, generating leakage current which is larger than the holding current of the silicon controlled rectifier dimmer; when the dc voltage of the on-time signal is greater than the bleed threshold voltage, the bleed current is turned off, typically the current flowing through the LED is greater than the holding current of the triac dimmer. The phase angle detection circuit can be integrated in the chip by using the digital filter, and a capacitor is not required to be used outside, so that the number of pins of the chip is saved, and the system cost is reduced; meanwhile, the bleeder circuit is integrated in the chip, so that peripheral application circuits are simplified; in addition, the invention can set the dimming curves with different phase angles by the dimming control signal. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (15)
1. The silicon controlled rectifier dimming phase angle detection circuit is characterized by at least comprising:
the bus voltage detection module receives and detects bus voltage;
the first comparison module is connected to the output end of the bus voltage detection module and compares the detection voltage of the bus voltage with the preset bus detection voltage to generate a pulse width modulation signal;
the on-time signal generating module is connected to the output end of the first comparing module and generates an on-time signal of the silicon controlled rectifier dimmer based on the pulse width modulation signal;
the digital filtering module is connected to the output end of the on-time signal generating module and is used for filtering the on-time signal;
the second comparison module is connected to the output end of the digital filtering module and compares the output voltage of the digital filtering module with the bleeding threshold voltage so as to generate a bleeding control signal; when the output voltage of the digital filtering module is smaller than the bleeding threshold voltage, the bleeding control signal controls to generate a bleeding current; when the output voltage of the digital filtering module is greater than the bleeding threshold voltage, the bleeding control signal controls the bleeding current to be turned off.
2. The silicon controlled dimming phase angle detection circuit of claim 1, wherein: the on-time signal generating module comprises a first switch and a first resistor, one end of the first switch receives a reference voltage, the other end of the first switch is grounded through the first resistor, the first switch is controlled by the pulse width modulation signal, and the on-time signal is output at a connection node of the first switch and the first resistor.
3. The silicon controlled dimming phase angle detection circuit of claim 1, wherein: the digital filtering module comprises an adder, a second switch, a third switch, a first capacitor and a second capacitor;
the input end of the second switch is connected with the output end of the digital filtering module, and the output end of the second switch is connected with the upper polar plate of the first capacitor, so that the output voltage of the digital filtering module is sampled; the lower polar plate of the first capacitor is grounded;
a first input end of the adder is connected with an output end of the second switch, and a second input end of the adder receives the on-time signal and is used for performing addition operation;
the input end of the third switch is connected with the output end of the adder, and the output end of the third switch is used as the output end of the digital filtering module and is used for sampling the output signal of the adder;
the upper polar plate of the second capacitor is connected with the output end of the third switch, and the lower polar plate is grounded;
wherein the control signals of the second switch and the third switch have opposite polarities.
4. The silicon controlled dimming phase angle detection circuit of claim 3, wherein: the capacitance value of the first capacitor and the capacitance value of the second capacitor are pF level.
5. The silicon controlled dimming phase angle detection circuit of claim 3, wherein: the digital filtering module further comprises a follower connected between the output end of the third switch and the output end of the digital filtering module, and the follower is used for isolating signals.
6. The silicon controlled dimming phase angle detection circuit of claim 3, wherein: the digital filtering module also comprises a switch control signal generating unit; the switch control signal generating unit comprises a high-frequency sampler and an inverter, wherein the high-frequency sampler is used for generating square wave signals; the phase inverter is connected with the output end of the high-frequency sampler and is used for generating an inverse signal of the output signal of the high-frequency sampler.
7. The silicon controlled dimming phase angle detection circuit of claim 1, wherein: the silicon controlled rectifier dimming phase angle detection circuit further comprises a reference voltage generation module, wherein the reference voltage generation module is connected to the output end of the digital filtering module, receives the dimming control signal and generates corresponding reference voltage according to the output voltage of the digital filtering module and the dimming control signal.
8. The silicon controlled dimming phase angle detection circuit of claim 7, wherein: the reference voltage generating module comprises a dimming unit and a clamping unit;
the dimming unit receives the output voltage of the digital filtering module and the dimming control signal and adjusts the waveform of the reference voltage based on the dimming control signal;
the clamping unit is connected to the output end of the dimming unit, and when the conduction time signal of the silicon controlled dimmer is larger than the maximum conduction time of the LED, the reference voltage clamp is positioned at a set reference voltage.
9. The silicon controlled dimming phase angle detection circuit of claim 8, wherein: the clamping unit comprises a second resistor, a comparator and a pull-down tube; one end of the second resistor is connected with the output end of the dimming unit, and the other end of the second resistor is used as the output end of the clamping unit; the input end of the comparator is respectively connected with the output end of the clamping unit and the set reference voltage; one end of the pull-down tube is connected with the output end of the dimming unit, the other end of the pull-down tube is grounded, and the control end of the pull-down tube is connected with the output end of the comparator.
10. A silicon controlled rectifier dimming phase angle detection method, which is implemented based on the silicon controlled rectifier dimming phase angle detection circuit according to any one of claims 1 to 9, wherein the silicon controlled rectifier dimming phase angle detection method at least comprises:
detecting bus voltage to obtain a conduction time signal of the silicon controlled dimmer, and digitally filtering the conduction time signal to obtain corresponding direct current voltage;
comparing the direct current voltage of the conduction time signal with a leakage threshold voltage to generate a leakage control signal, and generating a leakage current when the direct current voltage of the conduction time signal is smaller than the leakage threshold voltage; and when the direct current voltage of the on-time signal is greater than the bleeding threshold voltage, the bleeding current is turned off.
11. The silicon controlled rectifier dimming phase angle detection method of claim 10, wherein: the silicon controlled rectifier dimming phase angle detection method also comprises the step of generating corresponding reference voltage based on the direct current voltage of the conduction time signal and the dimming control signal;
when the on-time signal is less than the minimum on-time, the reference voltage is zero; when the on-time signal is greater than the maximum on-time, the reference voltage clamp is at a set reference voltage; when the on-time signal is between the minimum on-time and the maximum on-time, adjusting the waveform of the reference voltage based on the dimming control signal;
the minimum conduction time is the time detected by a phase cut angle of the silicon controlled dimmer after the bus voltage drop LED cannot be conducted; the maximum on-time is the maximum on-time of the LED.
12. The silicon controlled rectifier dimming phase angle detection method of claim 11, wherein: the minimum on-time and the maximum on-time satisfy the following relational expression:
wherein, Ton_maxIs the maximum on-time, VLEDIs the on-voltage of the LED, Vin_maxIs the peak value of the bus voltage, T is the period of the bus voltage, Ton_minIs the minimum on-time, V'busIs a preset bus voltage.
13. A bleed-off control system, characterized in that the bleed-off control system comprises at least:
the thyristor dimming phase angle detection circuit and the bleeder circuit of any one of claims 1 to 9;
the silicon controlled dimming phase angle detection circuit detects bus voltage to obtain a conduction time signal of the silicon controlled dimmer, and compares direct current voltage subjected to digital filtering of the conduction time signal with a discharge threshold voltage to obtain a discharge control signal;
the discharging circuit is connected with the output end of the silicon controlled dimming phase angle detection circuit, current discharging is controlled according to the discharging control signal, and discharging current is larger than maintaining current of the silicon controlled dimmer.
14. The bleed control system of claim 13, wherein: the leakage circuit comprises a leakage pipe, a third comparison module, a feedback resistor and a leakage current adjusting resistor; the discharge tube is connected with the discharge current regulating resistor in series and then connected with two ends of the bus voltage in parallel; the first end of the feedback resistor is connected between the discharge pipe and the discharge current regulating resistor; the first input end of the third comparison module is connected with the output end of the silicon controlled rectifier dimming phase angle detection circuit and the second end of the feedback resistor, the first input end of the third comparison module is connected with the discharge reference voltage, and the output end of the third comparison module is connected with the control end of the discharge pipe.
15. The bleed control system of claim 13 or 14, wherein: the bleed control system further comprises a first diode and a second diode; the positive electrode of the first diode is connected with the output of the silicon controlled rectifier dimming phase angle detection circuit, and the negative electrode of the first diode is connected with the input end of the bleeder circuit; and the anode of the second diode is connected with a discharge turn-off signal, and the cathode of the second diode is connected with the input end of the discharge circuit.
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| CN106793352B (en) * | 2017-04-06 | 2018-11-13 | 矽力杰半导体技术(杭州)有限公司 | LED drive circuit, circuit module with controllable silicon dimmer and control method |
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| CN108990213A (en) * | 2018-08-06 | 2018-12-11 | 杭州士兰微电子股份有限公司 | LED drive circuit and its dimming controlling method |
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